<template>
  <div class="">
    <pre>
      push => 返回数组长度
      var arr = [1,2,'a'].push('b')
      arr = 4
    </pre>
    <pre>
      [1,2,3].map(v => {
        if(typeof v === 'number') return
        return num * 2
      })
      => [undefined, undefined, undefined]
      map => array 当函数无任何返回值 -> undefined
    </pre>
  </div>
</template>
 
<script>
export default {
  name: 'arrTips',
  data () {
    return {
      msg:''
    }
  }
}
</script>
 
<style scoped lang="scss">
 
</style>